The present invention relates to an electrolysis cell consisting of a housing having an inlet and an outlet for the electrolyte passing through the cell. The housing accommodates monopolar electrodes, each of which consists of a number of parallel plates fixed to a common carrier element, and arranged in a staggered pattern so that the plates of one polarity extend into the gaps formed by the plates of the opposite polarity. At least one median electrode stack of one polarity with central electric power input is arranged between two electrode stacks of the opposite polarity.
The prior art includes monopolar cells of the design outlined above through which the electrolyte passes in a vertical direction and in which a multitude of electrode plates is arranged vertically in a monopolar pattern. The two outer electrode stacks are connected to the negative pole of a power source to serve as cathodes. These outer electrode plates are fixed to two carrier plates which serve as two side walls of the cell.
The plates are arranged in a vertical direction, equally spaced and parallel to one another. The inner electrode plates which constitute the median electrode stack are connected to the positive pole of a power source to serve as anodes.
The individual electrode plates are rectangular and are provided with two circular openings located symmetrically on the center line. The anode plates are fixed to two sleeves extending across the openings and are equally spaced, parallel to the longitudinal center lines of the sleeves. The cathode plates are rectangular in shape and have their free longitudinal edges provided with two semi-circular openings arranged so that a small annular gap is left between the sleeves and the cathode plates fixed to the two opposite carrier plates.
The cathode components are typically formed of steel, while the anode components are formed of titanium. The anode plates are coated with an activating layer of a known type on one or both sides.
The anode plates are lined up on one, or preferably several threaded stems, and are fixed in place by means of threaded sleeves and threaded rings. According to an embodiment of the invention with regard to the median electrode stack, the threaded sleeves are provided with annular crowns to which the anode plates with corresponding openings are welded.
While the cathode plate of the electrolysis cell of known design is free of mechanical problems, the cell is affected by certain disadvantages concerning the anode plates, i.e., the median electrode stack. The latter consists of a multitude of bolted components with more or less precise electric contact points which are sensitive to corrosion with consequent increased electrical resistance and voltage drops. The long threads and the areas of thin wall thickness of the threaded sleeve require complex fabrication procedures and are subject to distortion. The concentric power supply, for example, through two or three connecting bolts, is bound to entail an unfavorable distribution of current density across the rectangular electrode plate. Welding of the electrode plates to the threaded sleeve with annular crowns may easily cause warping because of the multiple concentric welded joints and this may, consequently, result in an irregular spacing of anode and cathode plates.